Specification of Red Onion: Each onion having light and dark red colour The sizes of red onion vary between 40 mm to 60 mm. Packed in 25 kg /50 Kg mesh bag as per customer requirements. ... 1 Kg of red onion consists of 12 to 13 onion of 45-55 mm. i.e. 13.5 tons in 20 feet one door box container.